There has been a constant demand for high purity water for research and intravenous admixtures. However, it has not yet proved possible to produce water free of everything. Since the water quality requirements vary from one project to another, the tolerable level and the nature of contaminants in the water of course also vary. Therefore comprises are made with respect to the quality, and the economic requirements in order to obtain water for specific needs. The most common contaminants found in high-purity water are metalic ions, gases, organic compounds, bacteria and their by-products, endotoxins, and mycotoxins.
Ideally, distillation should give water of the highest purity, since the process of purification is merely one of adding heat to convert the water to steam and then condensing the steam to recover the water in pure form. In practice this is not the case because of the difficulties involved in producing water free of all substances.
Many are now convinced that high purity water is not only ideal to have for some research, but is absolutely essential for many biomedical experiments, especially those requiring the injection of parenteral solutions. For this reason, many laboratory distillation devices have been introduced.
Among the patents that disclose distillation apparatus are U.S. Pat. No. 2,535,807 which discloses a laboratory still for the distillation of mixtures of liquids of varying boiling points. U.S. Pat. No. 3,896,003 discloses a distillation apparatus which may be cleaned without having to be dismantled. U.S. Pat. No. 4,239,601 discloses a water distillation apparatus with a volatile pollutant removal stage. U.S. Pat. No. 3,513,076 discloses an apparatus for high purity distillation that includes a scrubber for removal of entrained liquid from the heated vapor. U.S. Pat. No. 3,849,260 discloses a water distillation apparatus that automatically drains the boiling chamber after each use. U.S. Pat. No. 4,235,677 discloses an apparatus for continuous production of high purity bacteria free and endotoxin free water.
U.S. Pat. No. 4,313,786 to Smith discloses a magnetron solvent recovery system. U.S. Pat. No. 3,495,648 to Amadon discloses a microwave apparatus for evaporating liquid mixtures and U.S. Pat. No. 2,640,142 to Kim relates to a method of heating filamentory material with microwaves. The use of microwave energy in evaporation is disclosed in U.S. Pat. No. 3,607,667.